Low power and Lossy Networks (LLNs), e.g., sensor networks, have a myriad of applications, such as Smart Grid and Smart Cities. Various challenges are presented with LLNs, such as lossy links, low bandwidth, battery operation, low memory and/or processing capability, etc. One example routing solution to LLN challenges is a protocol called Routing Protocol for LLNs or “RPL,” which is a distance vector routing protocol that builds a Destination Oriented Directed Acyclic Graph (DODAG, or simply DAG) in addition to a set of features to bound the control traffic, support local (and slow) repair, etc. The RPL architecture provides a flexible method by which each node performs DODAG discovery, construction, and maintenance.
Neighbor Discovery (ND) protocols support a number of functions necessary to construct and maintain an IP network. For example, IPv6 ND allows IPv6 nodes/devices to discover each other's presence, determine each other's link-layer addresses, find routers, maintain reachability information for paths to active neighbors, etc. IPv6 ND has been modified to function in LLNs by using a proactive approach. For example, devices (e.g., grid mesh devices) proactively transmit IPv6 Neighbor Solicitation (NS) messages to support address resolution and maintain reachability information. A proactive approach to sending IPv6 NS messages is primarily used for two reasons: 1) the overhead associated with link-local multicast, which is typically used for ND in non-LLNs, is prohibitively expensive for a LLN, and 2) link qualities in LLNs vary continuously over time, and therefore must be actively tracked in order to maintain viable link mapping for LLN routing. Unfortunately, the use of proactive IPv6 NS messages in a LLN poses significant problems because it creates extensive control plane overhead, even when the NS messages are transmitted at a low rate.